You have to create PayPal REST sandbox credentials and copy/move api/config/Config.php.sav to api/config/Config.php. Insert the credentials into api/config/Config.php as client_id and client_secret for the correct environment.
The approval window will not close automatically, because the return_url is missing in the payload/payment_source/experience_context! After the approval, close the tab or window manually and go back to the checkout-window.
A running LAMP environment is necessary. Clone the git to the root folder of that installation.
git clone https://github.com/tozielinski/pp-php-ec-example.git
cd pp-php-ec-example/api/config
cp Config.php.sav Config.php
Now you must add your credentials in Config.php.
This project is licensed under the MIT License - see the LICENSE.md file for details.